I have a single lever Kohler kitchen faucet. The water comes out with so much pressure that if I am trying to rinse anything it makes water spray everywhere. The faucet has not always done this. Is there any way to make the water come out with less pressure other than to adjust the lever every time I turn it on?

Like Michael said, the aerator was the first thing that came to mind when I heard your account. The aerator restricts the flow of water, reducing the pressure exiting the faucet nozzle, and also introduces air into the flow of water exiting the faucet which further reduces the water's force. This reduces "splashout" while holding something under the water; the water stream will hit whatever is under it, the air will compress and buffer the water hitting the object, and then leave the stream. The remaining water has much less energy after this has happened, so it doesn't splash nearly as much.

With the aerator gone (or blown out or broken), you're getting a stream of solid water, which retains most of the energy it has upon leaving the faucet and will splash violently off of the first few things it hits.